New UTSC research suggests the search for life on planets outside our solar system may be more difficult than previously though.

New U of T Scarborough research suggests the search for life on
planets outside our solar system may be more difficult than previously
thought.

The study, authored by a team of international
researchers led by UTSC Assistant Professor Hanno Rein from the
Department of Physical and Environmental Science, finds the method
used to detect biosignatures on such planets, known as exoplanets, can
produce a false positive result.

The presence of multiple chemicals such as methane and oxygen in an
exoplanet’s atmosphere is considered an example of a
biosignature, or evidence of past or present life. Rein’s team
discovered that a lifeless planet with a lifeless moon can mimic the
same results as a planet with a biosignature.

“You wouldn’t be able to distinguish between them
because they are so far away that you would see both in one
spectrum,” says Rein.

The resolution needed to properly identify a genuine biosignature
from a false positive would be impossible to obtain even with
telescopes available in the foreseeable future, says Rein.

“A telescope would need to be unrealistically large,
something one hundred metres in size and it would have to be built in
space,” he says. “This telescope does not exist, and there
are no plans to build one any time soon.”

Current methods can estimate the size and temperature of an
exoplanet planet in order to determine whether liquid water could
exist on the planet’s surface, believed to be one of the
criteria for a planet hosting the right conditions for life.

While many researchers use modeling to imagine the atmosphere of
these planets, they still aren’t able to make conclusive
observations, says Rein. “We can’t get an idea of what the
atmosphere is actually like, not with the methods we have at our
disposal.”

There are 1,774
confirmed exoplanets known to exist, but there could be more than
100 billion planets in the Milky Way Galaxy alone. Despite the
results, Rein is optimistic the search for life on planets outside our
own is possible if done the right way.

“We should make sure we are looking at the right
objects,” he says, adding that the search for life within our
solar system should remain a priority. He points to the recent
discovery of a liquid ocean on Enceladus, one of Saturn’s larger
moons, as a prime example.

“As for exoplanets we want to broaden the search and study
planets around stars that are cooler and fainter than our own Sun. One
example is the recently discovered planet Kepler-186f, which is
orbiting an M-dwarf star,” says Rein.

Rein says locating a planet in a habitable zone while being able to
obtain a good resolution to model the atmosphere will help determine
what’s on the planet.

“There are plenty of reasons to be optimistic that we will
find hints of extraterrestrial life within the next few decades, just
maybe not on an Earth-like planet around a Sun-like star.”

Stay connected

We wish to acknowledge this land on which the University of Toronto operates. For thousands of years it has been the traditional land of the Huron-Wendat, the Seneca, and most recently, the Mississaugas of the Credit River. Today, this meeting place is still the home to many Indigenous people from across Turtle Island and we are grateful to have the opportunity to work on this land.